Two families with compound heterozygosity for adenine phosphoribosyltransferase deficiency.

Adenine phosphoribosyltransferase deficiency is a disorder in which 2,8-dihydroxyadenine (2,8-DHA) crystalluria is caused by a congenital deficiency in the enzyme adenine phosphoribosyltransferase (APRT). In most cases, APRT deficiency is caused by autosomal recessive inheritance of a homozygote of the mutant gene APRTQ0 or APRTJ, but there are also some cases in which the disorder is caused by the compound heterozygote APRTQ0 and APRTJ. In the patients described here, brown round crystals were found in their urinary sediment. Crystalluria was the first sign of APRT deficiency, thereafter confirmed by genetic screening for APRT*/Q0 and APRT*. We performed genetic screening for APRTQ0 and APRTJ in two families and diagnosed three cases of APRTQ0 /APRTJ compound heterozygote-type APRT deficiency. Genetic screening for APRTQ0 and APRTJ of family members is effective for early diagnosis and early treatment for family members.